A display device includes a lattice-shaped light-shielding pattern disposed on a transparent insulating substrate, and a color filter disposed on transparent insulating substrate, wherein the color filter overlaps with an edge portion of the light-shielding pattern. Moreover, a portion of the color filter that overlaps with the edge portion of the light-shielding pattern is rounded, and a portion of the color filter that does not overlap with the edge portion of the light-shielding pattern is planar.

Display device and method of manufacturing the same

GaN and AlGaN have shown great potential in next-generation high-power electronic devices; however, they are plagued by a high density of interface states that affect device reliability and performance, resulting in large leakage current and current collapse. In this review, the authors summarize the current understanding of the gate leakage current and current collapse mechanisms, where awareness of the surface defects is the key to controlling and improving device performance. With this in mind, they present the current research on surface states on GaN and AlGaN and interface states on GaN and AlGaN-based heterostructures. Since GaN and AlGaN are polar materials, both are characterized by a large bound polarization charge on the order of 1013 charges/cm2 that requires compensation. The key is therefore to control the compensation charge such that the electronic states do not serve as electron traps or affect device performance and reliability. Band alignment modeling and measurement can help to determi...

Electronic surface and dielectric interface states on GaN and AlGaN

This letter reports a normally-OFF Al2O3/GaN gate-recessed MOSFET using a low-damage digital recess technique featuring multiple cycles of plasma oxidation and wet oxide removal process. The wet etching process eliminates the damage induced by plasma bombardment induced in conventional inductively coupled plasma dry etching process so that good surface morphology and high interface quality could be achieved. The fully recessed Al2O3/GaN MOSFET delivers true enhancement-mode operation with a threshold voltage of +1.7 V. The maximum output current density is 528 mA/mm at a positive gate bias of 8 V. A peak field-effect mobility of 251 cm2/V·s is obtained, indicating high-quality Al2O3/GaN interface.

High-Performance Normally-Off ${\rm Al}_{2}{\rm O}_{3}/{\rm GaN}$ MOSFET Using a Wet Etching-Based Gate Recess Technique

Recent advances on dielectrics technology for SiC and GaN power devices

GaN based high electron mobility transistors (HEMTs) have demonstrated extraordinary features in the applications of high power and high frequency devices. In this paper, we review recent progress in AlGaN/GaN HEMTs, including the following sections. First, challenges in device fabrication and optimizations will be discussed. Then, the latest progress in device fabrication technologies will be presented. Finally, some promising device structures from simulation studies will be discussed.

https://www.mdpi.com/2079-9292/7/12/377/pdf

A Comprehensive Review of Recent Progress on GaN High Electron Mobility Transistors: Devices, Fabrication and Reliability

The conventional mesa isolation process in AlGaAs/InGaAs heterostructure FETs results in the gate contacting the exposed highly doped region at the mesa sidewalls, forming a parasitic gate leakage path. In this work, we suppress the gate leakage from the mesa-sidewall and enhance microwave power performance by performing an additional second mesa etching. The device gate leakage characteristics under high-input power swing are particularly investigated to reveal an improvement in device linearity, which is sensitive to the sidewall gate leakage. This modified device (M-HFETs) provides not only a higher linear RF output power but also a lower IM3 product than those characteristics in conventional HFETs.

Improved device linearity of AlGaAs/InGaAs HFETs by a second mesa etching

AlGaN/GaN high-electron-mobility transistors (HEMTs) with various field-plate (FP) and gate-to-drain distance extensions are fabricated and investigated. Experiments are carried out on 20 transistors. Their ON-state resistance (RON), OFF-state breakdown voltage (VBR), RF performance, and low-frequency noise are measured and studied. The FP extension is found to significantly improve the OFF-state breakdown voltage. However, the FP extension obviously weakens the frequency response and power added efficiency performance, because it increases the feedback Cgd. The FP extension is beneficial to the reduction of the electric field intensity at the gate edge of the device and reduces the probability of the injection of electrons into traps, resulting in the reduction of low- frequency noise.

Characteristics of AlGaN/GaN HEMTs With Various Field-Plate and Gate-to-Drain Extensions

A normally-OFF p-GaN gate AlGaN/GaN high-electron-mobility transistor with high ON-state resistance ( ${R}_{ \mathrm{\scriptscriptstyle ON}}$ ) uniformity was realized using a self-terminated digital etching technique. ${R}_{ \mathrm{\scriptscriptstyle ON}}$ uniformity control was improved by simultaneously using an AlN etching stop layer in an epitaxial design and a novel digital etching procedure. Digital etching includes the multiple-cycle oxidation and the wet etching of p-GaN layers and provides easy control of p-GaN removal depth and surface damage reduction at the gate-to-drain and gate-to-source spacing areas. Low-frequency noise and pulse measurements indicated that device surface traps and current collapse phenomena were suppressed.

High Uniformity Normally-OFF p-GaN Gate HEMT Using Self-Terminated Digital Etching Technique

In this study, an enhancement-mode (E-mode) AlGaN/GaN high electron mobility transistor (HEMT) using N2O plasma oxidation process has been performed Before the gate metal deposition, the AlGaN barrier layer was treated by 135 W N2O plasma for 240 s The surface native oxide of AlGaN was removed and a 4 nm high quality Ga2O3/Al2O3 compound insulator was simultaneously formed The threshold voltage of conventional depletion-mode (D-mode) GaN HEMT was −36 V and this value can be shifted to +017 after N2O plasma oxidation treatment beneath the gate metal This 4 nm Ga2O3/Al2O3 compound insulator oxidized by N2O can suppress the polarization charge density for E-mode operation of gate terminal and the gate leakage was also reduced simultaneously

Feng-Tso Chien

Papers

Improved device linearity of AlGaAs/InGaAs HFETs by a second mesa etching

Characteristics of AlGaN/GaN HEMTs With Various Field-Plate and Gate-to-Drain Extensions

High Uniformity Normally-OFF p-GaN Gate HEMT Using Self-Terminated Digital Etching Technique

Characterization of enhancement-mode AlGaN/GaN high electron mobility transistor using N2O plasma oxidation technology

High thermal stability and low hysteresis dispersion AlGaN/GaN MOS-HEMTs with zirconia film design